The chemical study of Ageratina deltoidea afforded grandiflorenic acid (1), ent-kaurenoic acid (2), and eight benzylbenzoates (3 - 10), two of them, 3,5-dimethoxybenzyl 2,3,6-trimethoxybenzoate (5) and 4-(β-d-glucopyranosyloxy)-3-hydroxybenzyl 2,6-dimethoxybenzoate (9), described for the first time. In addition, the new sesquiterpene lactone deltoidin C (13), together with the known 11 and 12, the phenolic compounds: ayanin, 2,6-dimethoxybenzoic acid, methyl 3,4-dihydroxycinnamate, chlorogenic acid, and 3,5-dicaffeoylquinic acid were also isolated. The structures of these compounds were determined by spectroscopic methods and chemical reactions. The antibacterial and antifungal activities of compounds 1 - 12 were evaluated on Staphylococcus aureus, Escherichia coli, and Candida albicans. Deltoidin A (11) was the most active antibacterial agent (MIC 16.0 μg ml-1 ) against E. coli, and the ent-kaurenoid derivatives (1 - 2) showed activity (MIC 31.0 μg ml-1 ) against S. aureus.